Guide

What Is Lean Body Mass?

Everything in your body that is not fat: muscle, bone, organs and water.

By Menang7, owner of LeanMassCalculator.com

Lean body mass (LBM) is your total body weight minus your body fat. It is the part of you that powers movement, supports your metabolism and keeps you strong as you age.

The scale cannot tell fat from lean tissue, which is why lean mass is a more useful number to track than weight alone.

What lean body mass includes

MuscleSkeletal muscle for movement, plus the smooth and cardiac muscle in your organs and heart.

BoneThe skeleton that supports your body and stores minerals.

OrgansHeart, liver, kidneys, brain and the rest of your internal organs.

Skin and tissueSkin, tendons and connective tissue.

WaterThe water held inside lean tissue, which is why hydration changes your readings.

Guide

Lean Body Mass vs Muscle Mass

They sound alike but measure different things. See what each one includes and which number is better to track.

Read the guide →

Lean body mass vs fat mass

Your body weight is made of two parts: fat mass and lean body mass. Fat mass is stored energy and some essential tissue. Everything else is lean mass. The formula is simple:

Lean body mass = body weight − fat mass, or equivalently, weight × (1 − body fat %).

Typical lean mass percentage

Category	Women	Men
Athletes	80–86%	87–94%
Fitness	76–79%	83–86%
Average	69–75%	76–82%
Above average body fat	68% or less	75% or less

Lean mass share is 100% minus body fat percentage, using the body fat ranges on this site.

How to measure lean body mass

DXA scanThe most practical accurate method. It also splits fat, lean and bone mass by body region.

Bioimpedance scalesConvenient for trends, but readings change with hydration.

Skinfold calipersCheap and repeatable when done by the same trained person each time.

FormulasEquations such as the Boer formula estimate lean mass from height, weight and sex.

Quick lean mass check

Why lean body mass matters

MetabolismLean tissue burns more energy at rest than fat does.

Strength and functionMore lean mass supports strength, balance and independence.

Healthy agingKeeping lean mass helps protect bones and mobility in later life.

Better progress trackingIt shows whether a diet is costing you muscle even when the scale drops.

How to build and keep it

Lift with progressionTrain each muscle at least twice a week and add load over time.

Eat enough proteinAbout 1.6–2.2 g per kg of lean mass daily.

Sleep 7–9 hoursRecovery is when muscle is repaired.

Avoid crash dietsA 10–20% deficit helps you keep muscle.

Frequently asked questions

What is lean body mass?
Lean body mass is everything in your body that is not fat: muscle, bone, organs, skin and water.

Is lean body mass the same as muscle mass?
No. Muscle is one part of lean body mass. Bone, organs, skin and water make up the rest, so lean mass is always larger than muscle mass.

What is a good lean body mass percentage?
About 76–86% of body weight for men and 69–79% for women falls in the fitness to average range.

How do I measure lean body mass?
A DXA scan is the most practical accurate method. Bioimpedance scales, skinfold calipers and formulas such as the Boer equation give estimates you can track over time.

Does lean body mass include water?
Yes. Lean tissue holds a large share of your body’s water, which is why scale and scan readings shift with hydration.

Is lean mass the same as muscle mass? Read more →

🧮Lean Mass CalculatorEstimate your lean body mass from height, weight, age and sex.Open →🧮Body Fat CalculatorEstimate your body fat percentage from height, weight, age and sex.Open →📏Lean Mass Index (LMI)Lean mass divided by height squared: a fairer way to compare builds.Open →💧Dry Lean MassLean mass without the water: what it means and why it matters.Open →📝Losing Lean Body Mass: Causes and FixesWhy muscle slips away during diets and aging, and how to protect it.Open →📝Healthy Lean Mass Percentage by AgeWhat is normal at 20, 40 and 60, and what to aim for.Open →

About Menang7, the author

This article is part of LeanMassCalculator.com, developed, owned and maintained by Menang7. For questions about lean mass or the calculators, Menang7 is the person to look for.

For personal medical or nutrition decisions, please also speak with a doctor or registered dietitian.